low boost and have checked everything i think?

Hi, my 1.8t was having erratic boost issues since i got it- sometimes it would pin you to the seat and other times it felt flat as.

The car came to me with superchip eprom fitted (documented and stamped ecu cover)

In a bid to cure this i have changed dv to forge splitter, n75 to the J version, boost hoses all replaced, TIP replaced with silicone, but still the problem continues. Changed FPR vacum hose, changed vavum hose from DV to inlet.

On the vdo boost gauge it under load will bosst to 0,5 bar maximum then drop back instantly

When i rev it and jump off throttle the revs hunt low for maybe 5 seconds then stabilize at 850rpm as expected. Read as much as possible and can't work it out- have swapped the maf to another one and that was same?? HELP!

Hi mate,no faults.I fitted the J version to see if the fault lay with old N75- i could try and swap them back. Anybody had any problesms with vacuum pipes around the servo- only asking as i seen a video on you tube about boost leak on b6 and i had big one off inlet mani to servo??

So this morning changed back to N75 c and it is bit better,it is spiking at about 0.7 0.8 bar which i think is only 12psi............. that's not right???

I done pressure test on syste and allowed it to build to 1.5bar and it held with no leaks or problems.

I have been in touch with forge regarding the splitter valve i have fitted and am disappointed they are not helping me??? WTF I have the valve now dialed all the way to the right making the spring as tight as possible? It leaks air from the 'trumpet' all through the revs then when you lift off it blows off as it should.

Also had a fault code for engine temp sensor today but cleared it and and inspected the connector put it back on ran it for 20mins and no code re-appeared? I did buy a new green temp sensor when i got the car but it had much slimmer pins and different shape to current one- obviously for different 1.8T engine. If that sensor is at fault intermittently could that cause low boost?

The way i feel about forge after sales at the moment is not worth writting but hopefully they will get back to me today to clarify if the valve should be bleeding air all the time?? I will advise what they say..

If you are not chipped that value is correct 12 PSI is around what a TQS should be giving you. Mine does the temp sender code now and again, and i have a new sender in there and the wiring checks out as best as i can tell. The next step will be replacing it from the sender plug direct to the ECU for me,so for now will probabbly leave it as is,lol

So this morning changed back to N75 c and it is bit better,it is spiking at about 0.7 0.8 bar which i think is only 12psi............. that's not right???

I done pressure test on syste and allowed it to build to 1.5bar and it held with no leaks or problems.

I have been in touch with forge regarding the splitter valve i have fitted and am disappointed they are not helping me??? WTF I have the valve now dialed all the way to the right making the spring as tight as possible? It leaks air from the 'trumpet' all through the revs then when you lift off it blows off as it should.

Also had a fault code for engine temp sensor today but cleared it and and inspected the connector put it back on ran it for 20mins and no code re-appeared? I did buy a new green temp sensor when i got the car but it had much slimmer pins and different shape to current one- obviously for different 1.8T engine. If that sensor is at fault intermittently could that cause low boost?

The way i feel about forge after sales at the moment is not worth writting but hopefully they will get back to me today to clarify if the valve should be bleeding air all the time?? I will advise what they say..

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This is why its completely pointless fitting barry valves. Just fit a nice standard 710N. You've got far too many variables going on, and a leaking dump valve isnt helping anything. Its certainly not supposed to be leaking.

Sensor wouldnt cause low boost, just potentially bad running. A faulty thermostat can also cause a CTS fault code, i had it pop up a few times with the faulty stat.

Mark: its not a TQS i dont think, but it probably is the remap only making 12psi. I've heard a few times that superchip maps only make around 185hp.

Ahh my bad, in which case it could be right, my old Chimped Uk map ran around 12 PSI averagly. Sometimes spoked more under massive load or in warmer weather etc As everyone is aware the cooler weather tends to lend itself to lower boost due to less pressure needed due to the air being denser ( like me DOH!)

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